None of these procedures have as yet been put to practical use, and it is doubtful whether any of them, unless we except perhaps the use of a staff in the rectum, would be justified for purely diagnostic purposes, considering the great risks involved. For the present, at least, the possibility of separating the secretion of one kidney from that of the other must be looked upon as depending chiefly upon accident, and in case of contemplated operation it is not possible to assure one's self of the integrity of the other kidney before the abdomen is opened. In many cases after opening the abdomen both kidneys may be examined before deciding upon further steps. Lawson Tait considers an exploratory incision distinctly indicated whenever abdominal disease not malignant threatens the life of the patient. The soundness of the other kidney, however, may be considered highly probable if in spite of demonstrated extensive disease of one kidney a sufficient quantity of urine with a normal amount of urea and salts continues to be formed. The SYMPTOMS arising from a large calculus producing destruction of the renal substance, when both kidneys are affected or one is insufficient to supplement the partial or total loss of the other, may closely resemble those of diffuse nephritis, either interstitial or parenchymatous, or perhaps it would be more correct to say that these forms of nephritis are the symptoms of such a change. Thus we may have polyuria, albumen, and casts, dyspnoea, dropsy, and uræmia. The enormous calculus described above as resembling a hippopotamus had given rise to no marked symptoms until palpitation, dyspnoea, and oedema were complained of; the heart was hypertrophied. The TREATMENT of calculi remaining in the kidney is, so far as medical means are concerned, that which has been already described, and, to say the least, is not a high degree of efficiency. Rest, diuretics, and solvents of the kind already spoken of, and narcotics, may afford relief, and in the case of quite small calculi, such as sometimes remain in the kidney even when not too large to pass through the ureter, solution is possible; but there is even less reason to suppose that large calculi can be dissolved in the kidney than that the tendency to their formation can be counteracted. Surgery, however, offers in some cases complete relief. Two operations have been undertaken for this purpose, of which the surgical details are here inappropriate, but the indications for which may very properly be discussed from a medical point of view. These are nephrotomy or nephro-lithotomy, the removal of the stone through an incision in the pelvis or secreting substance of the kidney; and nephrectomy, or the removal of the whole gland with its contents. It is obvious that the indications for these two operations are quite different, although cases are likely to arise where it will be well to change the plan from the former to the latter during the operation.